Compressor oil pump with filter

ABSTRACT

A hermetic compressor having a vertical crankshaft, the lower end of which is journalled in an outboard bearing which serves as part of a housing for an oil pump. The pump includes an impeller in the crankshaft which pumps lubricating oil from a casing sump while also centrifugally separating particulate contaminants from the oil. The oil pump supplies oil continuously to the bearings of the compressor and intermittently to a filter assembly when the crankshaft is rotated.

United States Patent 11 1 Hannibal Dec. 16, 1975 [73] Assignee: Tecumseh Products Company,

Tecumseh, Michv Primary Examiner-Richard J. Apley Assistant Examiner-Marvin Siskind Attorney, Agent, or Firm-Barnes, Kisselle, Raisch & Choate [22] Filed: Mar. 21, 1974 [21] Appl. No.: 453,279

1 ABSTRACT [52] US. Cl. 184/6.16; 417/372; 417/492;

184/624 A hermetic compressor having a vertical crankshaft, 51 1111. C1 F04B 17/00;FO1M 9/00 the lower end of which is joumalled in an Outboard [58] Field 61 Search 184/618, 6.16, 6.24; hearing which Serves as part of a housing for an Oil 308/134.1, 437; 417/902, 372; 415/88; pump. The pump includes an impeller in the crank- 2 7 7 shaft which pumps lubricating oil from a casing sump while also centrifugally separating particulate contam- 5 References Cited inants from the oil. The oil pump supplies oil continu- UNITED STATES PATENTS ously to the bearings of the compressor and intermittently to a filter assembly when the crankshaft is ro- 2,038,131 4/1936 Richard 184/616 med 1 3,448,918 6/1969 Cawley 3,664,461 5/1972 Leffers.... 184/616 3,692,435 9/ 1972 Iida 184/618 12 Claims, 3 Drawing Figures 3,692,435 9/1972 lida 417/902 I Davies 184/616 US. Patent Dec. 16, 1975 COMPRESSOR OIL PUMP WITH FILTER This invention relates to compressor lubricating systems and more particularly to a compressor oil pump and filter device.

An object of this invention is to provide an improved compressor oil pump and filter device which permanently removes solid matter from the main flow of lubricating oil without danger of lubrication failure due to clogging of the filter.

Another object is to provide a pump and filter of the above character which is durable, service free and economical to manufacture and assemble.

These and other objects, features and advantages of this invention will be apparent from the following description, appended claims and accompanying drawing in which:

FIG. 1 is a fragmentary side view of a hermetic compressor with a portion of the shell broken away and part of a gas compressor therein shown in section to illustrate the component parts of the oil pump and filter device embodying this invention.

FIG. 2 is an enlarged end view of the oil pump and filter device of FIG. 1.

FIG. 3 is an exploded perspective sectional view taken on the line 3--3 of FIG. 2 with the filter bag shown rotated 180 from its normal position to provide a rear view thereof.

Referring in more detail to the drawing, FIG. 1 illustrates a hermetic compressor embodying this invention with a single cylinder gas compressor 12 driven by an electric motor (not shown), both of which are hermetically enclosed in an outer shell or casing 14. Gas compressor 12 has a cylinder block and frame 16 and a vertical crankshaft 18 which is driven by the motor to reciprocate a piston 20 slidably received in a cylinder 22. Piston 20 is operably connected to crankshaft 18 by a connecting rod 24 with an end cap 26 secured thereto by bolts 28.

Gas compressor 12 has an improved oil pump and filter device 30 of the present invention partially submerged in a pool of lubricating oil 32 received in a sump formed by the bottom of casing 14. An outboard bearing 34 secured to frame 16 by cap screws 36 (FIG. 2) is utilized to provide part of the housing of pump 30. Crankshaft 18 is mounted for rotation in bearing 34 by a journal 38 formed at the lower end of the crankshaft which is slidably received in a bushing 40 press fit into a throughbore of housing 34. A thrust bearing plate 42 and a thrust plate 44 underlie crankshaft 18 and are secured to housing 34 by a pair of screws 46 extending through a pair of holes 48 and 48' disposed respectively in each of the plates. The lower end of crankshaft 18 bears on plate 42 which is made of a low friction, highly wear resistant material such as Norplex No. 825N asbestos phenolic plastic available from Norplex Fabricators of LaCrosse, Wis. Thrust plate 44 is preferably made of steel and serves as a back-up support for plate 42 as well as a cover for pump 30.

A cavity 50 in the lower face of housing 34 in cooperation with plate 42 defines in assembly an enclosed annular outlet chamber 52 which continuously communicates with an axial bore 54 in crankshaft 18 via hole 56 in plate 42, a radial groove 58 in the upper face of cover plate 44, and another hole 60 in plate 42. A pump impeller 62 is disposed within chamber 52 and is formed in the lower end of crankshaft 18 by an annular groove 64 in the end face of journal 40 and by a plurality of circumferentially spaced holes 66 which extend radially outwardly from groove 64 to chamber 52 and thereby provide impeller blades. In assembly groove 64 in cooperation with plate 42 define an inlet chamber 65 in impeller 62 which communicates with the pool of lubricating oil 32 through two registered pairs of underlying slots 68 and 68' extending respectively through plates 42 and 44.

Chamber 65 of impeller 62 intermittently communicates with an oil filter assembly 70 mounted on housing plate 44. Oil filter assembly 70 comprises a bulbshaped wire screen 72 open at one end and closed at the other, a corresponding filter bag 74 received therein and an elbow tube 76 having one end thereof received in the concentric open ends of bag 74 and screen 72 and fixed thereto by a ring clamp 78. The other end of tube 76, which has a flange 79 thereon, is fixedly received in one end of a passage 80, the other end of which communicates with .coaxially registered holes 82 and 84 disposed respectively in cover plate 44 and bearing plate 42. Oil filter 70 intermittently communicates with chamber 65 of impeller 62 through passage 80 and ports 82 and 84 via a blind bore 86 which extends axially in the impeller from the lower end face thereof and which is partially offset radially outwardly of groove 64 so as to open into the outer peripheral side wall 88 of groove 64 as shown in FIG. 3.

In the operation of hermetic compressor 10, the motor rotates crankshaft 18 which likewise rotates pump impeller 62 to thereby centrifugally pump lubricating oil continuously to the bearings of gas compressor 12 and intermittently to oil filter assembly 70. As indicated by the flow path lines and arrows 88 in FIG. 3, lubricating oil is drawn from pool 32 upwardly through ports 68' and 68 into inlet chamber 64 and discharged radially outwardly therefrom through passages 66 into outlet chamber 52 at a higher pressure. The pressurized oil in chamber 52 flows downwardly therefrom via hole 56 in plate 42, then radially inwardly via passage 58 in plate 44, and then upwardly again via hole 60 into the crankshaft oiling passageway 54 through which the oil is directed to the bearings of the compressor and to' suitable oil slinging ports for cooling of the compressor.

It is to be noted that concurrently with this main flow of oil to the compressor, an intermittent bypass flow of oil is established via filter 70 back to sump 32. Thus, once during each revolution of crankshaft 18, passage 86 in impeller 62 passes over at least a portion of hole 84 in plate 42, thereby intermittently placing filter assembly 70 in communication with chamber 65 of the impeller as shown in FIG. 3. This registration of passage 86 with hole 84 thus provides a rotary valve which intermittently bleeds or bypasses a portion of the pressurized oil in chamber 65 through filter assembly 70 back into the oil sump 32. In addition, a centrifuge operation occurs because the centrifugal action of impeller 62 tends to urge solid contaminants from the lubricating oil in chamber 65 outwardly toward wall 88, so that those particles which do not escape via passages 66 tend to collect in passage 86, since it is the radially outermost portion of chamber 65. Such particles then are flushed from passage 86 into filter assembly 70 once per crankshaft revolution by the intermittent flow of oil from chamber 65 to filter assembly 70.

In the pump and filter device 30 embodying this invention, filter assembly 70 is located on the discharge or high pressure side of the pump, which decreases the tendency of the filter to become clogged or plugged and hence provides a maintenance and service free pump and filter device having a long service life. The offset passage 86 of impeller 62 gradually separates particulate contaminants from the oil supplied to the bearings of the gas pump so that after a given number of running hours the oil supply will become increasingly purged of such contaminants as they eventually collect in filter 70. The location of the filter assembly in bypass relation to passage 54 insures that oil will continue to be supplied to the bearings of the gas pump even if the filter becomes completely clogged or plugged. These features thus cooperate to enhance the service life and decrease the maintenance and service of the gas pump in which this oil pump and filter device is utilized. Moreover, the integral impeller on the lower end of the crankshaft and the thrust bearing plate 42 and cover plate 44 sandwiched on the housing provide a compressor pump and filter device which is economical to construct and assemble.

I claim:

1. An oil pump and filter device for a gas compressor comprising in combination a crankshaft with a lubricating oil passage extending therein from one end thereof, a sump for lubricating oil disposed adjacent the crankshaft, a housing with said one end of the crankshaft journalled therein, a discharge chamber formed in cooperation with said housing adjacent said one end of said crankshaft, a centrifugal impeller received in said discharge chamber and fixed to said crankshaft for rotation therewith, said impeller having an inlet chamber therein communicating with both lubricating oil in the sump and said discharge chamber for receiving lubricating oil from the sump and discharging such lubricating oil into said discharge chamber in response to rotation of said impeller by the crankshaft, said inlet chamber having a generally annular outer peripheral side wall extending concentric with the axis of rotation of said crankshaft, a filter adapted to receive oil from said inlet chamber, and a valve communicating with said filter and said inlet chamber and responsive to rotation of said impeller to intermittently discharge a portion of the lubricating oil in said inlet chamber into said filter at least once per revolution of said impeller, said valve having a generally axially extending passage in said impeller opening into said outer peripheral side wall and a port positioned to at least partially communicate with said generally axially extending passage once per revolution of said impeller, said last mentioned port communicating with said filter.

2. The oil pump and filter device of claim 1 which also comprises a cover plate forming in cooperation with said housing said discharge chamber, said cover plate being secured to said housing.

3. The oil pump and filter device of claim 1 which also comprises a thrust bearing plate secured to said housing with the lower end of said crankshaft bearing thereon.

4. The oil pump and filter device of claim 2 which also comprises a thrust bearing plate with the lower end of said crankshaft bearing thereon, said thrust bearing plate being interposed between said housing and said cover plate.

5. The oil pump and filter device of claim 1 wherein said oil passage in the crankshaft continuously communicates with said discharge chamber whereby lubricating oil is continuously discharged from said discharge 4 chamber through said oil passage to lubricate the gas compressor.

6. An oil pump and filter device for a gas compressor having a vertical crankshaft and a sump for lubricating oil disposed below the crankshaft, said oil pump and filter device comprising a housing defining at least in part a discharge chamber adjacent the lower end of said crankshaft, an impeller received in said discharge chamber and fixed to said crankshaft for rotation the rewith, said impeller having an inlet chamber therein communicating with both lubricating oil in the sump and said discharge chamber for receiving lubricating oil from the sump and discharging such lubricating oil into said discharge chamber at a higher pressure than the oil in thesump in response to rotation of said impeller by the crankshaft, a bypass passage extending generally axially in said impeller, said bypass passage being in communication with said inlet chamber in the radially outermost part thereof relative to the axis of rotation of said impeller, a cover plate underlying said impeller and having a port therein positioned to intermittently communicate with said bypass passage in response to rotation of said impeller, and a filter means in communication with said port in said cover plate to receive lubricating oil discharged from said inlet chamber of said impeller through said bypass passage and to remove solid contaminants from such oil and retain such solid contaminants while returning filtered oil to said sump.

7. The oil pump and filter device of claim 6 wherein said inlet chamber comprises an annular groove in the lower end of the crankshaft and said impeller comprises at least one passage extending generally radially through the lower end of the crankshaft between and in communication with said inlet and discharge chambers and wherein oil to lubricate the gas pump is discharged from said discharge chamber through a passage extending through the lower end of the crankshaft and opening into a central portion of the lower end thereof.

8. The oil pump and filter device of claim 7 wherein the lower end of the crankshaft is joumalled in said housing.

9. The oil pump and filter device of claim 8 which also comprises a thrust bearing plate carried by said housing with the lower end of said crankshaft bearing thereon. 10. The oil pump and filter device of claim 6 wherein said filter comprises a filter bag open at one end and closed at the other, and a tube received at one end in the open end of said bag and secured thereto, the other end of said tube being received in a passage in said cover plate whereby said filter is disposed externally of said cover plate and in said oil sump.

11. An oil pump and filter device for a gas compressor comprising in combination a crankshaft with a lubricating oil passage extending therein from one end thereof to conduct oil for the lubrication of the gas compressor, a sump for lubricating oil disposed adjacent the crankshaft, a centrifugal impeller fixed to said crankshaft for rotation therewith and communicating with both lubricating oil in the sump and said oil passage for discharging lubricating oil drawn from the sump into said oil passage in response to rotation of said impeller by the crankshaft, filter means adapted to receive oil from said impeller and to remove solid contaminants from such oil and retain such solid contaminants while returning filtered oil to said sump, and a valve communicating with said impeller and said filter means and responsive to rotation of said impeller to in- 6 one end in the open end of said bag and secured thereto, the other end of said tube communicating with said valve .for conducting oil from said valve into the open end of said filter bag, said filter bag being disposed externally of said oil pump. 

1. An oil pump and filter device for a gas compressor comprising in combination a crankshaft with a lubricating oil passage extending therein from one end thereof, a sump for lubricating oil disposed adjacent the crankshaft, a housing with said one end of the crankshaft journalled therein, a discharge chamber formed in cooperation with said housing adjacent said one end of said crankshaft, a centrifugal impeller received in said discharge chamber and fixed to said crankshaft for rotation therewith, said impeller having an inlet chamber therein communicating with both lubricating oil in the sump and said discharge chamber for receiving lubricating oil from the sump and discharging such lubricating oil into said discharge chamber in response to rotation of said impeller by the crankshaft, said inlet chamber having a generally annular outer peripheral side wall extending concentric with the axis of rotation of said crankshaft, a filter adapted to receive oil from said inlet chamber, and a valve communicating with said filter and said inlet chamber and responsive to rotation of said impeller to intermittently discharge a portion of the lubricating oil in said inlet chamber into said filter at least once per revolution of said impeller, said valve having a generally axially extending passage in said impeller opening into said outer peripheral side wall and a port positioned to at least partially communicate with said generally axially extending passage once per revolution of said impeller, said last mentioned port communicating with said filter.
 2. The oil pump and filter device of claim 1 which also comprises a cover plate forming in cooperation with said housing said discharge chamber, said cover plate being secured to said housing.
 3. The oil pump and filter device of claim 1 which also comprises a thrust bearing plate secured to said housing with the lower end of said crankshaft bearing thereon.
 4. The oil pump and filter device of claim 2 which also comprises a thrust bearing plate with the lower end of said crankshaft bearing thereon, said thrust bearing plate being interposed between said housing and said cover plate.
 5. The oil pump and filter device of claim 1 wherein said oil passage in the crankshaft continuously communicates with said discharge chamber whereby lubricating oil is continuously discharged from said discharge chamber through said oil passage to lubricate the gas compressor.
 6. An oil pump and filter device for a gas compressor having a vertical crankshaft and a sump for lubricating oil disposed below the crankshaft, said oil pump and filter device comprising a housing defining at least in part a discharge chamber adjacent the lower end of said crankshaft, an impeller received in said discharge chamber and fixed to said crankshaft for rotation therewith, said impeller having an inlet chamber therein communicating with both lubricating oil in the sump and said discharge chamber for receiving lubricating oil from the sump and discharging such lubricating oil into said discharge chamber at a higher pressure than the oil in the sump in response to rotation of said impeller by the crankshaft, a bypass passage extending generally axially in said impeller, said bypass passage being in communication with said inlet chamber in the radially outermost part thereof relative to the axis of rotation of said impeller, a cover plate underlying said impeller and having a port therein positioned to intermittently communicate with said bypass passage in response to rotation of said impeller, and a filter means in communication with said port in said cover plate to receive lubricating oil discharged from said inlet chamber of said impeller through said bypass passage and to remove solid contaminants from such oil and retain such solid contaminants while returning filtered oil to said sump.
 7. The oil pump and filter device of claim 6 wherein said inlet chamber comprises an annular groove in the lower end of the crankshaft and said impeller comprises at least one passage extending generally radially through the lower end of the crankshaft between and in communication with said inlet and discharge chambers and wherein oil to lubricate the gas pump is discharged from said discharge chamber through a passage extending through the lower end of the crankshaft and opening into a central portion of the lower end thereof.
 8. The oil pump and filter device of claim 7 wherein the lower end of the crankshaft is journalled in said housing.
 9. The oil pump and filter device of claim 8 which also comprises a thrust bearing plate carried by said housing with the lower end of said crankshaft bearing thereon.
 10. The oil pump and filter device of claim 6 wherein said filter comprises a filter bag open at one end and closed at the other, and a tube received at one end in the open end of said bag and secured thereto, the other end of said tube being received in a passage in said cover plate whereby said filter is disposed externally of said cover plate and in said oil sump.
 11. An oil pump and filter device for a gas compressor comprising in combination a crankshaft with a lubricating oil passage extending therein from one end thereof to conduct oil for the lubrication of the gas compressor, a sump for lubricating oil disposed adjacent the crankshaft, a centrifugal impeller fixed to said crankshaft for rotation therewith and communicating with both lubricating oil in the sump and said oil passage for discharging lubricating oil drawn from the sump into said oil passage in response to rotation of said impeller by the crankshaft, filter means adapted to receive oil from said impeller and to remove solid contaminants from such oil and retain such solid contaminants while returning filtered oil to said sump, and a valve communicating with said impeller and said filter means and responsive to rotation of said impeller to intermittently bypass a portion of the lubricating oil from said impeller via said filter means to said sump at least once per revolution of said impeller.
 12. The oil pump and filter device of claim 11 wherein said filter means comprises a filter bag open at one end and closed at the other, and a tube received at one end in the open end of said bag and secured thereto, the other end of said tube communicating with said valve for conducting oil from said valve into the open end of said filter bag, said filter bag being disposed externally of said oil pump. 